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Ophthalmic Optics Block 11 > Environmental Applications > Flashcards

Environmental Applications Flashcards

(67 cards)

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1
Q

High mass impact for lenses

A

Drop ball test

Steel ball dropped from 50inches

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2
Q

High velocity impact

A

Pointed projective, fired at 150ft/sec

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3
Q

What are the two tests used to verify resistance

A

High mass impact (drop ball test)

High velocity impact

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4
Q

Glasses designed to be impact resistance: heat treatment

A

Tempering or toughening glass lenses, lenses are a heated to about 700C for 2-3 minutes and then cooled rapidly with both surfaces fannaed simultaneouslt
-the outside of the lens will cool first and shrink, thereby pulling inward on the outer layers. This creates tension or stress and result in outer protective shell and 2-3 times greater impact resistance

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5
Q

Making glass impact resistance: chemical treatment

A

Chemical tempering, the process of increasing the impact of resistance of glass lenses by immersing them in a bath of molten potassium nitrate
-this induces an exchange of the sodium ions in the glass surface with the 30% larger potassium ions. The result in a more tightly packed surface layer that creates a layer of tension

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6
Q

______ treatment of glass results in greater impact resistance

A

Chemical

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7
Q

_____ treatment of glass can be applied to objects of complex shape

A

Chemical

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8
Q

_____ treatment of glass is quick

A

Heat

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9
Q

_____ treatment equipment for glass is inexpensive

A

Heat

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10
Q

How is glass tempering verified

A

Polariscope

  • consists of two polarized filters, one on the top and one on the bottom of the instrument with their absorption are perpendicular (cross polarized)
  • a normal lenses placed between the Dolores appears uniformly dark
  • a tempered lens will demonstrate stress partners: Maltese cross
  • polariscopes rarely found in practice CEO’s
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11
Q

Specification of occupational safety lenses

A

Minimum coverage area

Markings

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12
Q

787+

A

Impact rated Plano

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13
Q

Z87-2+

A

Impact rated Rx

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14
Q

V in occupational safety glasses

A

Variable tint

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15
Q

Lens type: W and shade number

A

Welding

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16
Q

Lense type: UV filter

A

U and scale number

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17
Q

Lens type: visible light filter

A

L and scale number

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18
Q

Non-impact lenses

A

Z87

Z87-2

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19
Q

Enchroma lenses

A

Color deficiency

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20
Q

Oxy-Iso glasses

A
  • aimed at those with color deficiency or those working with veins and blood (nurses and phlebotomist)
  • enhances the O2 signal from hemoglobin under the skin, amplifies the perception of veins under the skin
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21
Q

Switch vision in space

A
  • two frames passed NASAs rigorous testing and will be worn by astronauts
  • supplies the interchangeable magnetic prescription lenses
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22
Q

3D printing and frame design

A

Companies can 3D print their frames now

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23
Q

Close caption classes

A

For movie theaters

Have the closed caption inside the lenses

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24
Q

Stick on bifocals

A

Put them where they want

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25
Snap spectacles
Smart glasses Recording as you go Snapchat Social media
26
Conduction technology and glasses
Bone conduction tech so you dont need earphones, controls music and calls
27
Smart glasses
- liquid lenses change shape according to the distance of objects - lenses made of glycerin inflexible membranes that’s move back and forth to change the curvature of the lens - distance in meter on the bridge - takes about 14 miliscedonds to change Rx
28
Oakley smart glasses
Snowboarding/skiing glasses - connect to internet - play music - show routes and elevation - show speed
29
Solution to reflection with anti-reflective coating:p ath condition
Where the AR coating applied to the lens surface is 1/4 of the wavelength of light thick, the reflected path from the back fo the coating will be a 1/2 wavenlerght longer. Light reflected form the back of the coating is this 180 degrees out of phase from light reflected from the front. If the amplitude of light reflected at each surface of the coating is equal when they will cancel each other out
30
Amplitude condition for AR coating
Where the amplitude of light reflected from each surface of an AR coating is equal and, if 180 degrees out of phase, will cancel each other out. For this to occur, the refractive index of the coating must equal to the square root of the refractive index of the lens material N(coating)=square root of n(lens)
31
If it is _____ out of phase, in antifrelfective coating, it will cancel each other out
180 degrees
32
Why do the multiple layers on anti reflective coating have different refractive indices
More wavelength specific
33
Corning
Original company that makes glass lenses and photochromics
34
Original glass photochromic manufacturers
``` Corning photochtomic 1.60-1.90 Very high quality Decades of normal use Reactions mediated by atoms of silver ```
35
Drive safe lenses by ZEISS
Designed to reduce glare while driving at night Designed to maintain an accurate view of the road, dashboard, near and side view mirrors Luminance design technology -changes in the size of the drivers pupils is taken into account while driving
36
Short fit progressive
Short corridor - ransitions quicker - fits in a smaller frame - B m,easurements of less than 30 is smaller
37
Occupational progressive
- lens designed to emphasize intermediate and near vision - computer use, office work - very wide inter, near-low leave of unwanted astigmatism in periphery. Widens corridor because less change in add power is required over a longer distance
38
Double segment flattop bifocals (double D)
-bottom-near -top-near -remainder-distance 0for people who work in confined spaces that need to see up close, above and below them, without moving their heads
39
DD occupational lens (tri)
Bottom-near Top-intermediate or near Remainder-distance
40
Electricians, mechanics, painters need what kind of lenses
Double segment flat top bifocals (double D)
41
Balance lenses
Lens placed in a frame which looks like the lens for the opposite eye to balance appearance and weight -balance/bal on Rx indicates the designated eye is not sighted, so the same number should be entered for both eyes
42
Bi-convex lenses
A lens style where both the front and back surfaces are plus
43
Bi-concave
A lens style where both front and back surfaces are minus
44
Distance only correction in one eye, near vision correction in the other eye- results in acceptable clear vision at both distances
Monovision
45
Eye that sees distance in monovision
Will be blurred up close and the yees that sees near will be blurred at distance
46
Which eye is usually used for distance vision in monovision
Dominant
47
Why is the term monovision misleading
The two eyes still work together to see clearly, but one eye sees more clearly than the other at each distance
48
Limitations of monovision
- distant objects appear slightly blurred - lack intermediate vision - doesn’t provide adequate near vision for sustained reading - although the two euyes are still working together, binocular vision is compromised, causeing a decrease in depth perception
49
Generally used to correct extreme hyperopia. Designed to limit the thickness and weight that a high powered lens would normally required, all of the power of the lens is concentrated in a small area in the center
Lenticular lens
50
Minus lenticular lens
Myodisc
51
Techniques to reduce thickness: frame shape and seize
- smaller lens opening - less wide, less tall, rounder the better - plus Rx: smaller a good idea but less impact than minus RX
52
Techniques to reduce thickness: frame type
- avoid rimless and semi-rimless frames | - full plastic frames hide thickness
53
Techniques to reduce thickness
``` Frame shape and size Frame type Lens edging choices to hide thickness Hi index lenses Roll and polish Centering the OC over the GC Edge painting-edge matched to frame color ```
54
Rolling and polishing to reduce thickness: pros
Exposed edges are polished to enhance finished, “invisible” look of lens
55
Cons of rolling and polishing to reduce thickness
Seeing rainbows around edges
56
Adaptation issues: base curve
- flatter BC result in thinner lense,s steeper BC have less distortion - pts should adapt to small BC changes within a week - happens with patients sensitive to subtle changes in vision, when patient gets a second pair of similar eyewear, or when the patient only replaces one lens - when possible, keep the BC similar/same between the two eyes and similar/same as previous BC
57
Giving roll and polishing to patients
Must talk to patients about it. Some patients hate it
58
Polycarb adaptation issues
Low abbe number: complaints about VA and chromatic aberration -visual distortion of colors
59
Adaptation issues with polarization
Some people have issues with it
60
Most common adaptation issues
Base curve Polycarbonate Polarization
61
Potentially the first example of sunaglasses
1790
62
D-specs
For light sensitivity | Maybe to hide a defamation
63
Edward Scarlett
1727 | Worlds oldest pair of specs with sides
64
Worlds oldest pair of specs with sides
Edward Scarlett in 1727
65
First known mass production of eyewear
Turn around time was 18 months | Not sure of the time
66
Eyewear in culture
1951 - marketing multiple types of glasses to women - not about Rx, about looks
67
Why does bono wear sunglasses
He has glaucoma and has light sensitivity

Ophthalmic Optics Block 11 (4 decks)

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